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<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div class="one">one</div>
    <div id="md">middle</div>
    <div>two</div>
    <script>
        var md = document.getElementById("md");
        var siblings = md.previousSibling;
        var siblings = md.previousElementSibling;
        console.log(siblilngs);
        var nextsibling = md.nextSibling;
        var nextsibling = md.nextElementSibling;
        console.log(nextsibling);
    </script>
</body>
</html>